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author | Martin Odersky <odersky@gmail.com> | 2014-05-05 18:34:59 +0200 |
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committer | Samuel Gruetter <samuel.gruetter@epfl.ch> | 2014-05-20 13:38:48 +0200 |
commit | 82c4db686d07ae8e91f157f5c8b55a1a76917941 (patch) | |
tree | 3024867516bdc571987207296046fe5bcd3ca566 /tests/untried/pos/t1756.scala | |
parent | 94ceb9895a539b05fd81c8abe040c276178b5507 (diff) | |
download | dotty-82c4db686d07ae8e91f157f5c8b55a1a76917941.tar.gz dotty-82c4db686d07ae8e91f157f5c8b55a1a76917941.tar.bz2 dotty-82c4db686d07ae8e91f157f5c8b55a1a76917941.zip |
Pos tests t17xx - t19xx
Diffstat (limited to 'tests/untried/pos/t1756.scala')
-rwxr-xr-x | tests/untried/pos/t1756.scala | 54 |
1 files changed, 0 insertions, 54 deletions
diff --git a/tests/untried/pos/t1756.scala b/tests/untried/pos/t1756.scala deleted file mode 100755 index 1d067c3b0..000000000 --- a/tests/untried/pos/t1756.scala +++ /dev/null @@ -1,54 +0,0 @@ - -/** -This is a tricky issue which has to do with the fact that too much conflicting -type information is propagated into a single implicit search, where the intended -solution applies two implicit searches. - -Roughly, in x + x * y, the first x is first typed as Poly[A]. That -means the x * y is then typed as Poly[A]. Then the second x is typed -as Poly[A], then y is typed as Poly[Poly[A]]. The application x * y -fails, so the coef2poly implicit conversion is applied to x. That -means we look for an implicit conversion from type Poly[A] to type -?{val *(x$1: ?>: Poly[Poly[A]] <: Any): Poly[A]}. Note that the result -type Poly[A] is propagated into the implicit search. Poly[A] comes as -expected type from x+, because the lhs x is still typed as a Poly[A]. -This means that the argument of the implicit conversion is typechecked -with expected type A with Poly[A]. And no solution is found. - -To solve this, I added a fallback scheme similar to implicit arguments: -When an implicit view that adds a method matching given arguments and result -type fails, try again without the result type. -*/ -trait Ring[T <: Ring[T]] { - def +(that: T): T - def *(that: T): T -} - -class A extends Ring[A] { - def +(that: A) = new A - def *(that: A) = new A -} - -class Poly[C <: Ring[C]](val c: C) extends Ring[Poly[C]] { - def +(that: Poly[C]) = new Poly(this.c+that.c) - def *(that: Poly[C]) = new Poly(this.c*that.c) -} - -object Test extends App { - - implicit def coef2poly[C <: Ring[C]](c: C): Poly[C] = new Poly(c) - - val a = new A - val x = new Poly(new A) - - println(x+a) // works - println(a+x) // works - - val y = new Poly(new Poly(new A)) - - println(x+y*x) // works - println(x*y+x) // works - println(y*x+x) // works - - println(x+x*y) // failed before -} |